Polyorganosiloxane latexes are widely used as raw materials for resin additives, fiber treatment agents, mold release agents, cosmetics, antifoaming agents, additives for a coating material, and the like. Various methods have been proposed as the method of producing a polyorganosiloxane latex. For example, Patent Literature 1 and Patent Literature 2 describe polyorganosiloxane latexes obtained by emulsion polymerizing organosiloxane in an aqueous medium.
Polyorganosiloxane in a latex exhibits different properties depending on the particle diameter. When a polyorganosiloxane latex is used as a raw material for resin additives, fiber treatment agents, mold release agents, cosmetics, antifoaming agents, additives for a coating material, and the like, a polyorganosiloxane latex having the particle diameter optimal to the application is required in order to exhibit the performance which each of these target products requires. Thus, polyorganosiloxane having a controlled particle diameter and particle diameter distribution is useful.
For polyorganosiloxane contained in the latexes produced by the methods described in these Patent Literatures, the mass average particle diameter (Dw) is 150 to 800 nm, particle diameter distribution (Dw/Dn) expressed as a ratio of the mass average particle diameter (Dw) to the number average particle diameter (Dn) is 1.2 or less (Patent Literature 1), the number average particle diameter is 100 nm or less, and the standard deviation of the particle diameter is 70 nm or less (Patent Literature 2) as described in these Patent Literatures. Unfortunately, the methods described in these Patent Literatures actually have difficulties to obtain polyorganosiloxane having the mass average particle diameter of 100 nm to 200 nm and Dw/Dn of 1.7 or less.
Automobile lights such as a taillight, a brake light, and a headlight for automobiles mainly include a lens made of a transparent resin such as a polymethyl methacrylate (PMMA) resin and a polycarbonate (PC) resin and a housing that supports the lens. Among these, the housing is partially exposed to the sunlight outdoors. For this reason, the housing formed of a material having high weatherability has been desired in these days.
In production of the automobile light in the related art, the lens is bonded to the housing with a hot-melt adhesive, and integrated. To increase productivity, recently, the lens is bonded to the housing by a vibration welding method in some cases. Here, the vibration welding method is a welding method utilizing frictional heat in which in the state where the periphery end of the lens is pressed against the periphery end of the housing, vibration having a amplitude of 0.5 mm to 2.0 mm and the number of vibration of 200 Hz to 300 Hz is applied to generate frictional heat between the lens and the housing; thereby, the lens and the housing are fused, bonded, and integrated. In such a vibration welding method, the finished bonded portion of the lens and the housing needs to have a good appearance.
For the material for vibration welding, a thermoplastic resin composition containing a graft copolymer containing a composite rubber-based polymer consisting of polyorganosiloxane including vinyl polymerizable functional group-containing siloxane and alkyl (meth)acrylate rubber is disclosed.
A thermoplastic resin molded body for automobile parts and casings for a variety of electrical appliances may be subjected to a plating surface treatment for forming a metallic film made of a material such as copper, chromium, and nickel on the surface of the molded body to enhance designability and other functionalities. Moreover, a metallization treatment for forming a metallic film of aluminum, chromium, or the like (thickness of several dozen nanometers to several hundred nanometers) may be performed on the surface of the thermoplastic resin molded body by a vacuum deposition method, a sputtering method, or the like.
In the latter metallization treatment, to enhance the brightness of the molded body, an undercoat layer is usually formed by coating or plasma polymerization in advance before performing metallization treatment. Further, to protect the metallic film obtained by metallization treatment, a top coat layer composed of a silicon-based material or the like is usually formed.
Thus, conventional metallization treatment needs many steps, a dedicated apparatus, and an expensive treatment agent, while the so-called “direct deposition method” eliminating the step for forming the undercoat layer is used these days. The designability of the molded body obtained by the direct deposition method easily changes according to the kind of resin materials and the state of the surface of the molded body. For this reason, one of important problems is to stably maintain a beautiful bright appearance of the surface without fogging.
For the resin material suitable for the direct deposition, Patent Literature 3 discloses a thermoplastic resin containing a rubber-containing graft copolymer prepared by graft polymerizing a vinyl-based monomer with a rubber-based polymer having specific particle diameter distribution. Moreover, Patent Literature 3 discloses a thermoplastic resin composition in which the mass average particle diameter of the rubber-based polymer and the proportion of the component (% by mass) have a specific relationship.
Meanwhile, automobile members tend to be lighter these days. For this reason, the automobile members need to have higher physical properties such as impact resistance than ever. In addition to high heat resistance, the level of a demand for a beautiful bright appearance has been increased year after year. Unfortunately, the thermoplastic resin composition disclosed in Patent Literature 3 cannot sufficiently meet the recent demand for high brightness and impact resistance.
Further, recent thermoplastic resin compositions used for vehicle members and construction members need high mechanical strength under a low temperature. Efforts have been made so far to improve the surface appearance and impact resistance of the molded article made from a composite rubber-based graft copolymer prepared from a polyorganosiloxane rubber and an acrylic rubber in combination and the performance of impact resistance. For example, Patent Literature 4 discloses a thermoplastic resin composition comprising a polyorganosiloxane/acrylic composite rubber-based graft copolymer in which the average particle diameter is 10 to 70 nm and the proportion of particles having a particle diameter more than 100 nm is 20% or less based on the total particle volume. Such a resin composition, however, cannot achieve the performance that sufficiently meets the recent demand.